TB-2000 March 2012 Page 1 of 4
Installation and
Maintenance of ESD Mats
Introduction
The purpose of an ESD worksurface is to aid in the prevention
of damage to ESD sensitive components and assemblies from
electrostatic discharge. An ESD worksurface provides protection in
the following two ways:
1. Providing an antistatic worksurface area that will limit static
electricity generation.
2. Removing the charge from a conductive object placed on the
worksurface.
A dissipative worksurface having a surface resistance of at
least 1 x 10E6, but less than 1 x 10E9 ohms is recommended
by worksurface standard ANSI/ESD S4.1. Dissipative materials
minimize the generation of static charges, and will dissipate a
charge slow enough so that a spark will not occur. Dissipative
materials are usually the preferred choice for bench top
worksurfaces.
Conductive materials are the quickest to remove a charge,
but they can also cause damage by discharging too rapidly.
Conductive materials are usually used as floor mats, which is
defined by ANSI/ESD S7.1 as less than 1 x 10E6 ohms.
General Grounding Guidelines
1. ANSI/ESD S20.20 requires that all conductors in an ESD
protected area, including personnel, must be grounded.
2. The ESD ground must be tied directly to and at the same
potential as the building or “green wire” equipment ground.
3. Per ANSI/ESD S20.20, the ESD control program can in no
way replace or supercede any requirements for personnel
safety. Ground fault circuit interrupters (GFCI) and other safety
protection should be considered wherever personnel might
come into contact with electrical sources.
4. All electrical outlets should be verified for proper wiring
configuration, resistance or impedance and GFCI function when
the mat is installed and periodically thereafter.
Common Point Grounds
A common point ground is defined by the grounding standard
ANSI/ESD S6.1, as:
1. A grounded device where two or more conductors are bonded.
2. A system or method for connecting two or more grounding
conductors to the same electrical potential.
Examples of common point grounds with ground cords are
illustrated below.
Figure 2. Other ground cords.
Figure 3. 09814 with screw allows ground cord to be bolted to mat
to keep cord from disconnecting.
Common point grounds are designed to provide ground for
worksurface mats, wrist straps, and other items.
NOTE: DO NOT DAISY CHAIN. Because of the high resistances
inherent to many types of protective surfaces, daisy chaining of
these materials can severely limit their ability to properly dissipate
and protect against static charges.
DESCO WEST
- 3651 Walnut Avenue, Chino, CA 91710 (909) 627-8178
DESCO EAST - One Colgate Way
, Canton, MA 02021-1407 (781) 821-8370 Web Site:
Desco.comTECHNICAL BULLETIN TB-2000
Made in the
United States of America
2012 DESCO INDUSTRIES INC.
Employee Owned
Figure 1. Typical common point grounds.
COMMON POINT GROUND
Per ANSI/ESD S6.1, Grounding section 4.1.1 “Every element to be
grounded at an ESD protected station shall be connected to the
same common point ground.”
ESD Handbook ESD TR20.20 section 5.1.3 Basic Grounding
Requirements “The first step in ensuring that everything in an
EPA is at the same electrical potential is to ground all conductive
components of the work area (worksurfaces, people, equipment,
etc.) to the same electrical ground point. This point is called the
common point ground. The next step in completing the ground
circuit is to connect the common point ground to the equipment
ground (third wire, green).”
WRONG!
RIGHT
Figure 4. ESD mats should never be grounded in series, that is
daisy chained.
